Puzzling sound coming from my SDA-1C
jazzandroll
Posts: 27
Good morning! My name is Diego and I’m writing from Italy. I’m looking for some advices concerning a problem I have since months. It all started with a strange noise coming from my right SDA-1C speaker, a sort of brief "prrr" that sometime I clearly hear while playing music. After this noise happens, I distinctly hear a low frequency reduction then, after few seconds (maybe 5 or 10, sometime more), everything is fine. At first, I thought it could be a matter of connections, so I opened the speaker carefully verifying that everything is ok, no loosing connections or the like. At this point, I think it could be the crossover….but….to be honest I don’t know exactly how to proceed, I mean that I’m not that experienced with electronics. In any case, starting from what I know about and from the drawings I have, I believe that I should look at the electrolitycs capacitors, since the other ones, being plastic type, should be fine. Otherwise, could it be a matter of inductors? Mostly the larger one? Has anyone of you already had such a problem? Is there anything I could be unaware of? Any suggestion will be seriously appreciated! Many thanks. Diego
Comments
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Inductors should be fine in 99.999% cases they do not wear out. I'm not sure what you're hearing. Tell us more about the system and what you're running gear wise.
Welcome to club Polk -
Hi, thanks for the answer. Actually, I was almost sure about the inductors; concerning the system, I'm currently using a Marantz SA-7001 SACD player and a Line Magnetic LM211ia tube amp (EL34) both absolutely well functioning given that I tested them in my secondary system and they work flawlessly. I really do not what to think, the noise is quite weird and it happens from time to time. As referred, it sounds just like the classic connection issue...how can I say.....guess a driver with a "dancing" connection
........the problem is that all connectors are ok. What about a possible coil damage in a driver? 
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that is absolutely a possibility. Magnet shifting is well documented as the old glue lets go. BUT I'd think it wouldn't come and go. Slowly push in on all 6.5" drivers evenly to see if you feel scratching as it goes in and out. Most of us glue our older drivers around the outside perimeter to help keep this from happening. Do a search here on here
here are some I found.
https://forum.polkaudio.com/discussion/184463/a-different-twist-on-the-magnet-gluing-process
https://forum.polkaudio.com/discussion/176345/my-2-3-tl-rebuild-and-so-the-journey-begins
there are a bunch just use the search function.
the crossover is also way past it's prime and a good candidate to get recapped. The second thing could be the polyswitch but your description is different that it's symptoms.
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Does it do this all the time, or regularly...like many times a minute or what have you?
Have you tried another amp or receiver also? -
@Pitdogg2: many thanks, I'll give it a look
@K_M: yes, I tried a different amp and this odd situation still is there....it's a matter of seconds .....now you hear it now you don't....I also thought to the copper braids as they move together with the cone and, maybe, after all these years they could be starting to loose their flexibility....I'll say more: the noise is similar to those scratches produced by an oxidized volume pot, you know what I mean?Post edited by jazzandroll on -
It could be that a magnet has shifted just a little bit, or something has shifted and the voice coil is rubbing. I had a MW6510 from an RTA11 start rubbing after a short while after the speaker was played for a while at moderate levels. It was an intermittent scratching sound, but nothing ever cut out. When I pressed on the speakers by hand there was no scratching. It was a mystery for a while. I figured once the voice coil got a little warm from use, something shifted enough that it would rub. I pressed at angles on each two speakers on the side that had the issue and eventually found one that rubbed when I only put a little force on it at an angle. I replaced it with a spare MW6510 I happened to have. This solved the issue.
I would recommend seeing if the issue occurs without the SDA cable connected. This will help identify which channel is truely the problem, or if there is something happening with the SDA circuit. Locate which side you hear the scratching and/or cut out, and then press each driver lightly at angles and see if one makes a scratching sound with much less force than the others. I would then swap that driver with the same one from the other channel and see if the sound or cut out moves to the other channel.
Hopefully this will help identify the problem. If it does not, let us know and we will try and help further. -
Upgrade every one of the capacitors and resistors regardless.
I believe your noise problem is a loose or worn out spider on the passive radiator.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Upgrade every one of the capacitors and resistors regardless.
I believe your noise problem is a loose or worn out spider on the passive radiator.
Take both passives out and inspect. If the spider has come loose two options.
1. They are pretty common on eBay try and find a pair of the same sw120 for instance or whatever your sw number is.
2. You can try to glue yours if it has come loose from the foam. We like aleenes-original-tacky-glue. I do not know if this is available in your spot on the globe but it works very well
If the spider is wore i have no suggestions for that. -
Upgrade every one of the capacitors and resistors regardless.
I believe your noise problem is a loose or worn out spider on the passive radiator.
Take both passives out and inspect. If the spider has come loose two options.
1. They are pretty common on eBay try and find a pair of the same sw120 for instance or whatever your sw number is.
2. You can try to glue yours if it has come loose from the foam. We like aleenes-original-tacky-glue. I do not know if this is available in your spot on the globe but it works very well
If the spider is wore i have no suggestions for that.
I agree with all he said above but want to add;
Check the spiders of all the mid-woofers too. I had a CS350 make those sounds and it was 2 or three of the spiders had come loose from the frames in various areas or completely. I also use Aleenes glue for this purpose with excellent results.Most people just listen to music and watch movies. I EXPERIENCE them. -
I've just reproduced a test cd containing low frequencies tracks from 20 to 100 Hz without any issue, no mechanical noise at all, I think this test would have been absolutely impossible to be performed from a compromised driver, isn't it? Given this, I'm considering a whole electro caps substitution.....regarding driver's suspensions, they're in a perfect shape and the same can be applied to the spiders, I checked them all and everything's fine.
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This may or may not tell you if the driver is ok, but worth a try. Using an ohm meter on each driver, slowly pushing them in, observe the reading on the meter.
The reading should change without showing an open circuit while pushing on them. If you get an open circuit then that's likely the culprit.
You may be able to get a reading from the binding post but may not be accurate, attaching to the driver would be best.
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This may or may not tell you if the driver is ok, but worth a try. Using an ohm meter on each driver, slowly pushing them in, observe the reading on the meter.
The reading should change without showing an open circuit while pushing on them. If you get an open circuit then that's likely the culprit.
You may be able to get a reading from the binding post but may not be accurate, attaching to the driver would be best.
I like this actually but I must agree that the XO be taken out of the circuit. There will be far too many varibles with the XO in the circuit.
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jazzandroll wrote: »Hi, thanks for the answer. Actually, I was almost sure about the inductors; concerning the system, I'm currently using a Marantz SA-7001 SACD player and a Line Magnetic LM211ia tube amp (EL34) both absolutely well functioning given that I tested them in my secondary system and they work flawlessly. I really do not what to think, the noise is quite weird and it happens from time to time. As referred, it sounds just like the classic connection issue...how can I say.....guess a driver with a "dancing" connection ........the problem is that all connectors are ok. What about a possible coil damage in a driver?
Have you by chance checked the tubes? Tubes can make strange noises when they are going bad out of bias any number of things. Since tube gear actually can use the speaker to listen so to speak a different speaker will likely not play the same with the amp. Unless your other speakers are the same SDA, the other speaker will present a far different load. worth checking IMO -
So you took the drivers out and tested for loose spiders?Most people just listen to music and watch movies. I EXPERIENCE them.
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jazzandroll wrote: »I've just reproduced a test cd containing low frequencies tracks from 20 to 100 Hz without any issue, no mechanical noise at all, I think this test would have been absolutely impossible to be performed from a compromised driver, isn't it? Given this, I'm considering a whole electro caps substitution.....regarding driver's suspensions, they're in a perfect shape and the same can be applied to the spiders, I checked them all and everything's fine.
The heat and potential minor swelling of the voice coil can come from higher frequencies and a wide range. That was the case with mine. It sounded like a dirty volume knob at times, but very faint. broken spiders have usually had a light clacking or buzzing sound at certain frequencies. Your test should have exposed that, but sometimes it can happen at a higher frequency if the spider only has a crack in it.
My driver would pass the press and ohm test when it was cold, and even seconds after I heard the scratching and powered down to press the driver, it appeared fine. It was only after I started pressing at some angles that I found one rubbed much easier than any of the others with a very small mount of pressure in the right direction combined with moving it back and forth. -
Hi again guys, thanks for the advices. Getting back to my problem, given that I don't have any testing instrument (just a meter) I cannot go deep into the question; at the moment, I checked the four drivers both hearing them that investigating for mechanical issues but they are ok, or so it seems. Sonically they sounds good, cosmetically they are almost perfect and, as said, this noise is absolutely electronic, just like a loosing contact. Very irritating since it only appears for few seconds.....I'm going to check the 2 caps today as I think their filtering function could have changed (or occasionally be higher) due to aging.Post edited by [Deleted User] on
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jazzandroll wrote: »given that I don't have any testing instrument (just a meter)
If it reads ohms, did you check each driver for a possible open circuit when lightly pressing on the cone? Like I said earlier, it may not show anything but it possibly could.
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jazzandroll wrote: »given that I don't have any testing instrument (just a meter)
If it reads ohms, did you check each driver for a possible open circuit when lightly pressing on the cone? Like I said earlier, it may not show anything but it possibly could.
Hi....no, actually I didn't....I mean I only checked their ohm values, but NOT while pushing 'em....I'm going to repeat the measure this afternoon....who knows? -
Have you checked your Interconnects and Speaker Wires? Swapped your Interconnects around? Might be something to look into.
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Mike Reeter wrote: »Have you checked your Interconnects and Speaker Wires? Swapped your Interconnects around? Might be something to look into.
Yesss....I did it....obviously they are in perfect shape....believe me when I say this is a bothersome situation.....most of all, the duration of this odd phenomenon makes its identification difficult
.....the fact is that it's clearly an electronic noise, absolutely not mechanic, the "sound" of the noise (allow me using this description) pushes me in that direction. -
All this talk of certain sounds reminded me of this
https://youtu.be/cvUhtSe-p6Y
Sorry had to. Best of luck diagnosing the issue OP!Just a dude doing dude-ly things
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Can you post a pic of the crossover? Do any of the caps appear to be leaking? Broken or cold solder joints?
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Can you post a pic of the crossover? Do any of the caps appear to be leaking? Broken or cold solder joints?
Actually I took a picture of it few days ago but it's slightly out of focus....in any case no trace of leaking or unusual appearance of its components. Concerning a cold solder joint, to be honest, it's hard to believe such a thing after 25 years of perfect functioning. Getting back to an eventual capacitors substitution, what if their values should be slightly different? Commercial available values are 44uF an 22uF while 40 and 20 are the original...... do you think could it be a problem? -
jazzandroll wrote: »Can you post a pic of the crossover? Do any of the caps appear to be leaking? Broken or cold solder joints?
Actually I took a picture of it few days ago but it's slightly out of focus....in any case no trace of leaking or unusual appearance of its components. Concerning a cold solder joint, to be honest, it's hard to believe such a thing after 25 years of perfect functioning. Getting back to an eventual capacitors substitution, what if their values should be slightly different? Commercial available values are 44uF an 22uF while 40 and 20 are the original...... do you think could it be a problem?
If 20uf and 40uf are not available, try two 10uf in parallel for 20uf, 18uf and a 22uf for 40uf.
Try and stay within 5% of the specified value. 3% even better.Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
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Here is a thread that may interest you.
SDA's and tubes
https://forum.polkaudio.com/discussion/comment/2316561#Comment_2316561"Sometimes you have to look to the past to understand where you are going in the future"Anger is just anger. It isn’t good. It isn’t bad. It just is. What you do with it is what matters.
You can use it to build or to destroy. You just have to make the choice. Jim Butcher
Harry / Marietta GA -
jazzandroll wrote: »Concerning a cold solder joint, to be honest, it's hard to believe such a thing after 25 years of perfect functioning.
That's exactly what they do. They work for a long time then the joint cracks, generally from vibration, like inside a speaker cabinet.
Probably not the issue, but to be frank, why wouldn't you check for it? Diagnosing would be to cover all the likely and possible culprits.
Web pic of cold joint.
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jazzandroll wrote: »Concerning a cold solder joint, to be honest, it's hard to believe such a thing after 25 years of perfect functioning.
That's exactly what they do. They work for a long time then the joint cracks, generally from vibration, like inside a speaker cabinet.
Probably not the issue, but to be frank, why wouldn't you check for it? Diagnosing would be to cover all the likely and possible culprits.
Web pic of cold joint.
Wow! Quite surprising....a cracked solder joint in other words....never seen something like this...in any case, this afternoon I carefully checked inner connections and I also looked for some driver's damage but none.....everything's fine. The only (good) news is that "the noise" didn't show itself.....maybe all this moving around has solved my issue 😅 -
westmassguy wrote: »jazzandroll wrote: »Can you post a pic of the crossover? Do any of the caps appear to be leaking? Broken or cold solder joints?
Actually I took a picture of it few days ago but it's slightly out of focus....in any case no trace of leaking or unusual appearance of its components. Concerning a cold solder joint, to be honest, it's hard to believe such a thing after 25 years of perfect functioning. Getting back to an eventual capacitors substitution, what if their values should be slightly different? Commercial available values are 44uF an 22uF while 40 and 20 are the original...... do you think could it be a problem?
If 20uf and 40uf are not available, try two 10uf in parallel for 20uf, 18uf and a 22uf for 40uf.
Try and stay within 5% of the specified value. 3% even better.
I'll follow your tips, thanks!
